泛喜马拉雅地区乌头属（毛茛科）的分类学研究

Approximately 400 species are now recognized in the genus Aconitum (Ranunculaceae). The Pan-Himalayan region is the largest distribution center of the genus Aconitum, with about 200 species recorded to occur in this region. The taxonomy of the genus is notoriously difficult because of its most complicated variation patterns in morphological character. Moreover, the scantiness of specimens available in the Pan-Himalayan region for study character variations at population level, is the major causes leading to errors in taxonomical treatment. The previous taxonomic treatments of Aconitum in the region have been mainly based on rather limited herbarium material (many new taxa were described from only a single collection, i.e. the type collection) and not dealing with all the species in the region as a whole. Consequently, errors in taxonomic treatment, particularly on species level, are rather prevalent in the genus. These mainly include misinterpretation of the identity of species, description of old species as new. The knowledge of both macro- and micro-morphological characters (such as root anatomy, floral micromorphology, palynology, and cytology) for the genus is very poor until now. This project aims to address all these basic taxonomic problems of Aconitum from the whole Pan-Himalayan region. After a critical survey of all the relevant literature and herbarium specimens, extensive field observations, and an in-depth investigation of all the macro- and micro-morphological characters, chromosomal characters, and DNA barcodes as well, we will carefully evaluate variation patterns of all these characters and determine their taxonomic applicability at species level. Our taxonomic decisions will be made based strictly on the results of our assessment of characters. Our final objective is to produce a thorough, monographic revision of Aconitum from the Pan-Himalayan region, which should synthesize all the information that is known about the genus. This project will help us gain a better understanding of species composition and differentiation in the Pan-Himalayan region, and will also provide invaluable basic scientific information for the utilization and protection of the resources of Aconitum, in which many species are medicinally and/or ecologically important.

毛茛科乌头属全世界约400种。泛喜马拉雅地区是乌头属最大的分布中心，记载约200种。由于乌头属形态变异复杂；泛喜马拉雅地区标本过少，难以运用居群概念考察形态变异；前人常在只有模式标本的情况下描述大量新种，也并未将该地区乌头属作为一个整体来研究。因此该地区乌头属还存在大量种级水平的分类学问题（名实不符、新分类群不能成立等）。此外，一些具有潜在分类价值的性状研究仍显不足。本项目拟结合经典分类学（文献、标本和野外考察）和现代系统学（细胞学、解剖学和DNA条形码）研究方法，基于居群水平深入研究乌头属的宏观和微观性状，阐明性状变异式样，确定性状的分类和系统学价值，进行种及种下等级水平的正确划分和命名，完成该地区乌头属专著水平的分类修订。乌头属具有重要的药用价值，澄清其分类学问题可增加泛喜马拉雅地区的物种组成和分化等问题的理解，同时为植物资源的利用和保护提供科学资料。

毛茛科乌头属全世界约有400余种，主要分布在北半球温带地区，泛喜马拉雅地区是乌头属植物的重要分布区。由于缺乏野外观察和标本不够丰富等原因，有些种类的分类处理仍存在争议。本项目通过形态学、细胞学和分子系统学等方法对乌头属中存在的分类学问题开展了综合研究，进行了该地区乌头属全面的分类修订。取得的结果如下：（1）基于计算机图像处理对乌头属的宏观形态性状进行了数量化和标准化，为分析乌头属形态性状的变异幅度奠定了基础。（2）采用扫描电镜和光学显微镜技术，对乌头属47种62份样品的叶表皮特征进行了比较分析，表皮细胞形状、气孔形状和类型、表皮毛等性状在种内稳定但种间差异明显，可作为可靠的分类学性状。（3）采用石蜡切片技术，观察了23种乌头属的根和叶的解剖结构，根和叶的解剖结构在种间存在差异，角质层厚度、表皮细胞厚度、叶片厚度和叶肉细胞等性状的变化模式可以为研究乌头属植物在进化过程中的生态适应提供参考。（4）对15种乌头属植物进行了细胞学研究，染色体基数为x=8，牛扁亚属中的黄毛乌头为四倍体（2n=32），乌头亚属均为为二倍体（2n=16），核型不对称性有2B、3B、2C和3C型。（5）对乌头属28种34个个体进行了浅层基因组测序，拼接获得了完整的叶绿体基因组，长度介于155,430-157,586 bp, 共含有112-113个独有基因，78-79个蛋白质编码基因，30个tRNA基因和4个rRNA基因；此外，选取了乌头属40种68个个体的叶绿体基因组和核糖体DNA的5个不同序列组合，比较种内种间遗传距离、barcoding gap，构建系统发育树，物种鉴别的成功率。标准条形码能区分35%的物种，叶绿体基因组和ITS组成的超级条形码可以区分57.5%的物种。（6）结合文献查阅和标本研究，对乌头属的形态性状在居群间和居群内的变异式样进行了比较分析，明确该地区共有乌头属植物115种13变种，将18种4变种降为异名，初步澄清了工布乌头复合群、显柱乌头复合群、直序乌头复合群等种类中长期存在的名实混乱。本项目对泛喜马拉雅地区的药用植物乌头属采用多学科综合手段进行了系统的分类修订，为资源合理利用提供了科学依据，也为该地区生物多样性形成的基础理论研究奠定了基础。